Storage apparatuses have the following function. In the case of the occurrence of unexpected accidents, data stored in a certain storage apparatus (copy source storage apparatus) is transferred to a storage apparatus at a remote site (copy destination storage apparatus) and is backed up therein. In this case, if data groups transferred to the copy destination storage apparatus are not written in the same order as the data groups were written into the copy source storage apparatus, data consistency between the copy source storage apparatus and the copy destination storage apparatus is lost.
Accordingly, the copy source storage apparatus transfers data groups to the copy destination storage apparatus such that the consistency of the order of the data groups is guaranteed in the copy destination storage apparatus. For example, the copy source storage apparatus stores update data received from a server in a dedicated memory which is divided into units of generations, each unit including a certain capacity, and transfers groups of the update data in units of generations to the copy destination storage apparatus. Then, the copy destination storage apparatus receives the data groups in units of generations from the copy source storage apparatus, and loads the received data groups into a storage device of the copy destination storage apparatus. In this manner, the copy source storage apparatus transfers data groups in units of generations, thereby guaranteeing the consistency of the order of data groups.
A technique for copying data while guaranteeing the consistency of the order of data groups is utilized, not only in an open system constructed using a Unix (trademark)/Intel (trademark) Architecture (IA) server, but also in a system constructed using a mainframe (hereinafter referred to as a “mainframe system”).
Examples of the above-described related art are disclosed in Japanese Laid-open Patent Publication Nos. 2002-312125 and 2004-280779.
However, in the above-described related art, it takes time to load transferred data into a copy destination storage apparatus. More specifically, in a copy destination storage apparatus, every time a disk is accessed, a position in the disk is specified and a disk head is moved to the specified position. Since the copy destination storage apparatus writes data groups into the disk in the order in which the data groups have been stored in a dedicated memory, it randomly accesses the disk. Accordingly, the disk head randomly moves every time a data item is written into the disk. As a result, in the copy destination storage apparatus, when accessing the disk, it takes time to move the disk head, and thus, it takes time to load data.